NXS: Native XML processing in Sybase RDBMS

Sybase's flagship database product, Adaptive Server Enterprise provides Native XML processing (NXS) support. In this paper we present our experience related to query processing and indexing of XML data natively. XML documents are commonly represented as trees. Various tree annotation schemes have been proposed in literature. We use pre-order tree traversal to annotate the tree. This annotation scheme is fundamental part of our approach to native path indexes. We present our industrial strength XPath query engine that exploits the annotation scheme and the path indexes for efficient query processing. One of the key components of the XML engine is an abstract Application Programming Interface(API) named "Path Processor". This API acts as a bridge between query execution engine iterators and access paths. This paper describes the primitives provided by the API on sets of nodes resulting from scans over the XML indexes. The physical query operators in query plans exploit these primitives provided by the path processing API.